The units of your answer will be in au/year. 3. to give you a better perspective of how fast these orbital speeds really are, convert the orbital speeds you just calculated from au/year to miles/hour. 1 au/year = 10,604 miles/hour. record your answers in the table below. table mean orbital radius (au) (copy from #6 in part a) period (earth years) (copy from #6 circumference of orbit (au) orbital speed (au/year) orbital speed (miles/hour) 0.39 object mercury venus earth mars jupiter saturn uranus neptune pluto 0.73 1.0 1.5 5.2 a) 0.4 0.62 1.0 1.9 11.9 29 9.4 83 19 30.1 39.53 165 248